Kyesh was a masked, robed humanoid of indeterminate species who was often seen accompanying Naaya vas Nedas on her various travels. It was he that helped her build their ship, the Transcension, and he who helped her out when the two were living together on Omega. A powerful biotic, Kyesh had to use his skills on a variety of occasions, the most prominent of which being the assault on a slaving ring on Gurlorn, an attack that was led by the Paladins.
Secretive and cryptic to a fault, Kyesh refused to give out his true species when interacting with others on the Cerberus Daily News forum. Only Naaya knew his species, something that changed when it was later revealed that he was a human -- a species that Kyesh himself had claimed to loathe. Kyesh's name turned out to be Silas Gray, and Silas was actually born on Omega, before being sold to the Church of Dis, a cult whose base was located on the planet Kurlaan.
Additionally, it was revealed that Silas's Cabalist teacher of whom he'd spoken of on the Cerberus Daily News forum, was named Varana. Varana was a cruel and ruthless teacher, and taught Silas the values of biotic strength, self-reliance, and being locked in a room. Varana first met Silas on Kurlaan, and offered to help him take down the Church of Dis and kill their leader, Ell Raan Zirax, in exchange for agreeing to be Varana's apprentice. To make a long story short, the plan fell to pieces when Silas discovered the brutal experiments the Church was conducting. He wanted to destroy the cult's headquarters, but Varana wanted to save the eezo stored there. There was a confrontation, and the two separated.
Silas made it out of the building, but not fast enough -- the explosion burned off part of his face. Silas found a mask and robes in a nearby escape shuttle, and took on the name Kyesh, which in a turian language means 'nobody.' He then went to Omega, and found Naaya, and the rest is history.
Currently, Kyesh's location is unknown.